Fix date cache in strict mode.

src/date.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 745 matching lines @@
   if (date_cache_version_holder[0] == date_cache_version) {
     return;
   }
   date_cache_version = date_cache_version_holder[0];
 
   // Reset the timezone cache:
   timezone_cache_time = NAN;
   timezone_cache_timezone = UNDEFINED;
 
   // Reset the date cache:
-  cache = Date_cache;
-  cache.time = NAN;
-  cache.string = null;
+  Date_cache.time = NAN;
+  Date_cache.string = null;
 }
 
 
 // -------------------------------------------------------------------
 
 function SetUpDate() {
   %CheckIsBootstrapping();
 
   %SetCode($Date, DateConstructor);
   %FunctionSetPrototype($Date, new $Date(NAN));
@@ skipping 54 matching lines @@
     "toGMTString", DateToGMTString,
     "toUTCString", DateToUTCString,
     "getYear", DateGetYear,
     "setYear", DateSetYear,
     "toISOString", DateToISOString,
     "toJSON", DateToJSON
   ));
 }
 
 SetUpDate();